Pelagic calcification and fate of carbonate production in marine systems

• Main Author: De Bodt, Caroline
• Other Authors: Chou, Lei, Bernard, Alain, Engel, Anja, Delille, Bruno, Sabbe, Koen K., Regnier, Pierre, Lancelot, Christiane
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: Universite Libre de Bruxelles 2010
• Subjects: Sciences de la terre et du cosmos; Sciences exactes et naturelles; Biogeochemistry; Ocean acidification; Global warming; Coccolithophores > Climatic factors; Coccolithophores > Biscay; Bay of (France and Spain); Biogéochimie; Mer > Acidification; Réchauffement de la Terre; Coccolithophorales > Facteurs climatiques; Coccolithophorales > Gascogne; Golfe de (Espagne et France); Bay of Biscay; Emiliania huxleyi; calcification; coccolithophore
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210156; https://dipot.ulb.ac.be/dspace/bitstream/2013/210156/2/a93b5370-985d-4fd0-8b55-9538628cdaa1.txt; https://dipot.ulb.ac.be/dspace/bitstream/2013/210156/5/cba89749-8873-4822-9c67-740e89f90db8.txt; https://dipot.ulb.ac.be/dspace/bitstream/2013/210156/1/9eb7bffa-fbc1-4c87-81bb-ebdcacda804b.txt

Human activities have contributed to the increase in atmospheric greenhouse gases such as carbon dioxide (CO2). This anthropogenic gas emission has led to a rise in the average Earth temperature. Moreover, the ocean constitutes the major sink for anthropogenic CO2 and its dissolution in surface waters has already resulted in an increase of seawater acidity since the beginning of the industrial revolution. This is commonly called ocean acidification. The increase in water temperature could induce modifications of the physical and chemical characteristics of the ocean. Also, the structure and the functioning of marine ecosystems may be altered as a result of ocean acidification. Phytoplankton productivity is one of the primary controls in regulating our climate, for instance via impact on atmospheric CO2 levels. Coccolithophores, of which Emiliania huxleyi is the most abundant species, are considered to be the most important pelagic calcifying organisms on Earth. Coccolithophores are characterized by calcium carbonate platelets (coccoliths) covering the exterior of the cells. They form massive blooms in temperate and sub-polar oceans and in particular along continental margin and in shelf seas. The intrinsic coupling of organic matter production and calcification in coccolithophores underlines their biogeochemical importance in the marine carbon cycle. Both processes are susceptible to change with ocean acidification and warming. Coccolithophores are further known to produce transparent exopolymer particles (TEP) that promote particle aggregation and related processes such as marine snow formation and sinking. Thus, the impact of ocean warming and acidification on coccolithophores needs to be studied and this can be carried out through a transdisciplinary approach. The first part of this thesis consisted of laboratory experiments on E. huxleyi under controlled conditions. The aim was to estimate the effect of increasing water temperature and acidity on E. huxleyi and especially on the calcification. Cultures were ...